OpenTok .NET Server SDK. 60 second Delay using .NET Framework 4 and TLS 1.3 OpenTok .NET Server SDK. 60 second Delay using .NET Framework 4 and TLS 1.3

OpenTok .NET Server SDK. 60 second Delay using .NET Framework 4 and TLS 1.3

Yukari Dumburs

Symptom

After the Feb 18 TLS 1.3 enablement, some customers using OpenTok .NET SDK experience ~60 second delays in API operations (e.g. CreateSession).

In some environments this may result in request timeouts, operation failures, or unexpected latency before a response is returned.

This behaviour has been observed specifically when:

  • .NET Framework 4 is used
  • TLS 1.3 is negotiated
  • Expect: 100-continue is enabled

Applies To

Resolution

Primary recommendation
Upgrade to the latest OpenTok .NET SDK version (v3.20.2), which includes a mitigation for this behavior.
 
Alternative recommendation
If upgrading is not immediately possible, you can disable Expect: 100-continue manually in the application as shown below. This removes the delay while continuing to use TLS 1.3.
 
System.Net.ServicePointManager.Expect100Continue = false;

Cause

This behaviour is specific to .NET Framework 4 under TLS 1.3 with Expect: 100-continue enabled. It does not reproduce on OpenTok .NET Server SDK operations under TLS 1.3 with modern .NET.

Additional Information

OpenTok .NET SDK release note: https://github.com/opentok/Opentok-.NET-SDK/releases 

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